Knead 75 g icing sugar, butter, flour and egg in a mixing bowl first with the dough hooks of the hand mixer, then quickly with your fingers to a smooth dough. Form the dough into a ball, wrap in foil and chill for approx. 30 minutes.
Wrap the dough from the foil and divide it into 2 equal pieces. Form dough pieces into a roll, divide each roll into approx. 8 pieces of the same size and form into balls. Press the balls flat, place a chocolate drop on each ball.
Roll out the dough and form into a ball again.
Place the dough balls on a baking tray lined with baking paper, leaving a gap of approx. 1 cm between them. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 15 minutes.
Let the biscuits cool down for about 5 minutes, turn them in remaining icing sugar and let them cool down on a cake rack.